Explain the effects of two naturally occurring toxins on the human body

Explain the function and use of two different plants as medicines, for humans or animals

Determine three different applications for animal tissue culture

Extract from Course Notes

ACTIONS OF ENZYMES IN HUMANS & ANIMALS

The following comments are "generalised". They provide an overview of the type of chemical processes involved. These comments should not however, be taken as being specific to any one type of animal (or human).

Enzymes are chemical substances which can change other substances by a process called fermentation. Fermentation is the process which occurs in the brewing of beer and in the decomposition of dead matter. Enzymes are chemicals very like proteins in composition and they have three major properties:

They can bring about chemical change in other substances without themselves being changed in the process;

They can also achieve those changes inside the body in conditions of mild heat and comparatively mild acidity or alkalinity. In a laboratory, such changes would require conditions of great heat and the use of strong acids or alkalis; and

It takes only a very small amount of an enzyme to achieve big changes.

Enzymes are therefore very powerful chemicals indeed and they are specific to certain tasks. One particular enzyme will carry out one job and no other. Some enzymes can break down only some carbohydrates while others only act on protein.

Chemical or enzyme action starts in the mouth with the action of the enzyme Ptyalin which is found in saliva and is produced by the salivary glands. This enzyme acts on the starch in the food, converting it into the simpler chemicals such as the sugar maltose.

The food in the mouth, having been ground up, mixed with saliva, and the chemical breakdown having started, is swallowed in the form of a bolus and travels down the oesophagus into the stomach where it joins the food already there. In the stomach, there are two enzymes, pepsin and rennin, and one chemical, hydrochloric acid, whose chemical formula is HCl. HCl is a strong mineral acid and is produced by the glands in the stomach wall. It makes the contents of the stomach very acidic.

When mixed together, the enzymes and hydrochloric acid form gastric juice whose pH (the level of acidity or alkalinity) is between 1 and 2 - very acid indeed! The function of the acid in the stomach is to further breakdown the food and to prevent rotting (or putrefaction) of the mixture of undigested and partly digested food.

The enzyme Pepsin here acts on proteins in the food, breaking them down into simpler compounds.

By the time all these actions have taken place, the food is no longer recognisable as such but is now a semi-fluid which is called chyme. The chyme now passes slowly through the sphincter from the stomach into the small intestine in a series of spurts. An important point to remember is that no food is absorbed in the stomach. The only things which are absorbed through the wall of the stomach are alcohol and some drugs but these cannot be called food.

At this stage, the food that was originally placed in the mouth has undergone the following processes:

it has been chewed up and ground into fine particles, mixed with saliva and gastric juice and converted into chyme;

some starch has been converted into sugar by the enzyme ptyalin in the mouth;

some starch has been converted into sugar by the enzyme amylase in the mouth;

some protein has been broken down by the enzyme pepsin in the stomach;

the pH has been lowered and further dissolving has taken place by the action of hydrochloric acid in the stomach.

The stomach acts as a container or a reservoir which holds up the passage of food for some time so that it can be collected and acted upon by the gastric juice. Once the chyme enters the small intestine, it is moved along continuously by the muscular contractions of the wall of the intestine. This action is called peristalsis and is the same as the action which moves the food bolus down the oesophagus.

In the small intestine, the chyme is acted upon by the following juices which are added to it as it passes along the length of the intestine:

Intestinal juice or succuss entericus as it is called

Pancreatic juice from the pancreas

Bile stored in the gall bladder (in the liver).

The most active digestion takes place in the small intestine as at this stage the carbohydrates and proteins have only been partly digested and the fats have hardly been affected at all.

Succuss entericus is produced by glands in the lining of the intestine and it is made up of enzymes such as:

maltase;

sucrase;

lactase.

These enzymes break down complex sugars into the simple sugar glucose. Another enzyme, peptidase, continues with the breakdown of proteins.

Pancreatic juice contains one enzyme, amylase, which breaks down sugars into glucose. In addition, it contains three enzymes (chymotrypsin, peptidase and trypsin) which break down proteins as well as lipase which acts on the lipids or fats. The pancreas also produces two regulatory hormones, insulin and glucagon, which control the levels of glucose in the blood.

Bile from the liver acts on the fats in the chyme, breaking them down into very fine droplets which mix with the watery chyme. Normally oil and water do not mix, but if the oil is in fine droplets and is mixed vigorously with the water, they form a mixture called an emulsion.

The very fine drops of fat are then broken down by the action of the enzyme lipase to a substance called glycogen and fatty acids. These will be discussed when we consider digestion in the ruminant. The other function of bile is to reduce the acidity of the acid chyme which has come from the stomach. The chyme in the small intestine is alkaline 0- this is brought about by bile.

From the small intestine, the chyme passes into the colon which, together with the caecum, makes up the large intestine. At this stage, the original food has been broken down completely in the following way:

carbohydrates to simple sugar glucose

proteins to amino acids

fats to glycerol and fatty acids.

Most of these products have been absorbed through the wall of the small intestine. What is left passes into the rectum and out through the anus. The main function performed in the colon is the removal of water from the chyme - this water is absorbed into the body and reused by the animal. This is a most important function. Without it, the animal would have to consume vast quantities of water, most of which would be wasted by passing straight through the body.

AFTER YOUR STUDIES

When you understand fundamental biochemistry, as
you learn in this course; you will have an enhanced ability to
understand the care and management of both humans and animals.

For farmers, pet owners or wildlife managers, you will
have a basis for understanding the foods that animals eat, health
disorders they might encounter, and physiological processes that happen
in their bodies.

For anyone working in health care or fitness, you can
better understand the processes in the human body, understand human
nutrition, the way in which diseases affect the body, how medicines
work, and much more

Biochemistry is not only useful to biochemists.

Fitness leaders can do their job much netter when they understand fundamental biochemistry

Health industry workers, from pharmacy assistants to medical receptionists can benefit from this course.

Graziers, animal breeders, zoo keepers, veterinary nurses,
and anyone else who works with animals will enhance their abilities at
work, by studying biochemistry

Entrepreneurs, salesmen and
business owners who develop or distribute products or services in health
or animal industries, will potentially gain a whole additional
perspective and context to their job, through studying this course.

Secure online payments

Find us on:

Phone 07 5562 1088

International +61 7 5562 1088

The information given is for general information and should not be regarded as advice in any matter. ACS Distance Education disclaims all and any liability in relation to any act or omission which is
done in reliance to the information provided in this web site. While every effort is made to ensure that we display correct information on our website, errors can occur. ACS Distance Education disclaims liability or responsibility for orders or complaints arising from such errors, including
(but not limited to): pricing, fees and course requirements. ACS Distance Education reserves the right
to decline orders arising from such errors.